1. Field
Embodiments relate to a display device and an image signal compensating method, and more particularly, to a display device and an image signal compensating method which improve a display quality.
2. Description of the Related Art
A display device, such as a liquid crystal display (LCD) or an organic light emitting diode display, generally includes a display panel having a plurality of pixels and a plurality of signal lines, and a driving unit which drives the display panel. Each pixel includes a switching element connected to the signal line, a pixel electrode connected thereto, and an opposed electrode. The driving unit includes a gate driver which supplies a gate signal to the display panel, a data driver which supplies a data signal to the display panel, and a signal controller which controls the data driver and the gate driver.
The pixel electrode is connected to the switching element such as a thin film transistor (TFT) and a data voltage is applied to the pixel electrode. The opposed electrode is formed on an entire surface of the display panel and a common voltage Vcom is applied thereto. The pixel electrode and the opposed electrode may be disposed on the same substrate or on different substrates.
For example, the liquid crystal display includes two display panels which have the pixel electrode and the opposed electrode and a liquid crystal layer having a dielectric anisotropy interposed therebetween. The pixel electrodes are formed in a matrix and are connected to the switching elements, e.g., thin film transistors (TFTs), so that the data voltage is sequentially applied to every row of the pixel electrodes. The opposed electrode is formed on the entire surface of the display panel and a common voltage Vcom is applied thereto. A voltage is applied to the pixel electrode and the opposed electrode to generate an electric field in the liquid crystal layer and an intensity of the electric field is adjusted to adjust a transmittance of light which passes through the liquid crystal layer to obtain a desired image.
The display device receives an input image signal from an external graphic controller and the input image signal contains luminance information of each pixel and the luminance has a predetermined number. The pixel is applied with a data voltage corresponding to desired luminance information. The data voltage which is applied to the pixel is represented as a pixel voltage in accordance with a difference from a common voltage which is applied to the common electrode and each pixel displays the luminance represented by a gray scale of the image signal in accordance with the pixel voltage. In this case, in the liquid crystal display, in order to prevent deterioration occurring when an electric field in one direction is applied to the liquid crystal layer for a long time, a polarity of a data voltage with respect to a reference voltage for every frame, every row, every column, or every pixel may be reversed.
Recently, a higher quality image can be provided as the resolution of the display device becomes higher, so that the resolution of the display device is increased. Therefore, as the resolution becomes higher, a time to charge the pixel with the data voltage may be shortened. Particularly, if the polarity of the data voltage is reversed, a time to charge the data voltage to be a target data voltage may be insufficient.
In order to supplement the charging time, generally, a pre-charging method is used. The pre-charging method previously transmits a pre-charging voltage before applying a target data voltage to each pixel so that a pixel voltage for representing a target luminance may be rapidly reached at the time of main-charging the pixel.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.